Cam-forming method and apparatus

ABSTRACT

A method and apparatus wherein a predetermined linear pattern is scanned at a given rate while a cylindrical cam blank is rotated at a related rate and cut or marked at an axial cutting position which varies instantaneously with lateral changes in the linear pattern whereby the end of or marking on the finished cylindrical cam forms a helical pattern corresponding to the linear pattern.

United States Eatent McKusick 1 Apr. 10, 1973 [541 CAM-FORMING METHOD AND 2,333,985 11/1943 Clark ..51'/100 APPARATUS 3,267,813 8/1966 Walstrom ..90/13.3

4 1. [76] Inventor: John c. McKusick, 3495 E. Rice 5 3 Boulevard, Los g s Calif 90023 1221 Filed= Aug-18,1970 Primary Examiner-G11Weidenfeld 21 Appl- 172 1 Att0rneyHarris, Kern, Wallen & Finsley Related US. Application Data [63] Continuation-impart of Ser. No. 752,217, Aug 13, [57] ABSTRACT 1968, Pat. No. 3,601,005.

A method and apparatus wherein a predetermined [52] 11.8. C1. ..90/l3.9, 51/100 R linear P is Scanned at a given rate While a y [51] Int. Cl ..B23c 1/18 dfical Cam blank is rotated at a related rate and Cut [58] Field of Search ..90/13.4, 13.7, 13.9; marked at an axial cutting position which varies 51/100 R; 83/410; 82/14 A stantaneously with lateral changes in the linear pattern whereby the end of or marking on the finished cylin' [56] References Cited drical cam forms a helical pattern corresponding to the linear pattern. UNITED STATES PATENTS 2,179,211 11/1939 'Flygare ..51/100 11 Claims, 5 Drawing Figures CAM-FORMING METHOD AND APPARATUS This application is a continuation-in-part of my application for Cam-Forming Method and Apparatus, Ser. No. 752,217 filed on Aug. 13, 1968 and to be issued on Aug. 24, 1971 as U.S. Pat. No. 3,601,005.

This invention relates generally to methods and apparatus for forming cams and more particularly to a method and apparatus for cutting or marking a helical pattern on a cylindrical cam blank which corresponds to a predetermined linear pattern. The invention is particularly appropriate for forming barrel cams with the helical pattern cut on the surface of a hollow or solid cylindrical cam blank or completely through the wall of a hollow cylindrical cam blank.

Finished barrel cams are usually mounted for rotation on their longitudinal axes and typically impart a desired linear motion in the axial direction to a cam follower. A pair of barrel cams with identical helical patterns cut on their ends are often used in mating relation, one as a cam and the other as a follower, to accomplish this axial movement. In contrast, finished plate and face cams formed by the invention of my parent patent application are usually mounted for rotation on their center axes and typically impart a desired linear motion in a direction normal to the axis.

Conventional cylindrical and barrel-type cams are usually formed by cutting cam blanks in conformity to a master cam. Preparation of a master cylindrical or barrel-type cam is therefore a necessary step which requires substantial time, effort and money. It is also a very critical step since any flaw in the master cam shape will automatically recur in the duplicate cam copied therefrom.

The manufacturing of such master cams by conventional methods can be done only by a skilled craftsman, and involves several difficult and tedious manual steps. Each step must be performed very carefully, and even when done so, there is a constant chance for error throughout the operation. Furthermore, whenever a cam of a different shape or specification is needed, it is necessary to go through the complete painstaking process all over again.

Accordingly, it is a primary object of the present invention to eliminate the time, expense, and potential for error inherent in the tedious conventional preparation of master cylindrical and barrel-type cams, and to provide a new and improved method and apparatus for forming such master cams.

Another object is to provide a method and apparatus of the foregoing character which is relatively inexpensive, easy to perform and operate, and requires very little time to produce a finished cam of precise specifications.

A further object is to provide a method and ap paratus of the foregoing character wherein the desired pattern of the cam is laid out in a linear pattern defined in rectangular coordinates, the cam blank being cut or marked to form a helical pattern which corresponds to the linear pattern.

A more specific object is to provide an apparatus of the foregoing character which includes scanner means for scanning the linear pattern at a predetermined rate to sense its shape relative to a reference line, and includes cutter means for cutting the walls of the cylindrical cam blank to form a helical pattern which corresponds to the shape of the linear pattern. A related object is to provide drive means for rotating the cam blank relative to the cutter means at a rate proportional to the predetermined scanning rate of the scanner means.

Another object is to provide an apparatus of the foregoing character which includes means for varying the axial cutting distance between the cutter means and a reference plane normal to the longitudinal axis about which the cam is rotated so that the axial cutting distance is always proportional to the instantaneous lateral displacement of the linear pattern relative to the reference line.

Still another object is to provide varying means in apparatus of the foregoing character for moving the scanner means laterally relative to the linear pattern to keep the scanner means directly above the linear pat tern.

A further object is to provide an apparatus and method of the foregoing character which produces cams having a basic pattern successively repeated. A related object is to produce cams having a basic pattern alternated with its reflection as well as with its reversal.

The foregoing as well as other objects and advantages of the present invention may be more clearly understood by reference to the following detailed description when considered with the drawings, which by way of example only, illustrate one form of apparatus for forming cams and one method for forming cams embodying the invention.

In the drawings:

FIG. 1 is a side elevational view of a preferred embodiment of a cam-forming apparatus;

FIG. 2 is top sectional view of the embodiment of FIG. 1 taken along line 2-2 in FIG. 1;

FIG. 3 is an end elevational view taken along line 3 3 in FIG. 1 showing a tracer stylus contacting a prototype template at the first end of its linear pattern, with cutter means cutting the outside surface of a cylindrical cam blank into a helical pattern;

FIG. 4 is a side view taken along line 44 in FIG. 2 showing gear means for rotating a cam blank at a rate proportional to the movement of the template relative to the tracer stylus; and

FIG. 5 is a side view of a portion of FIG. 1 showing the cutter means cutting completely through the outside surface of a cylindrical cam blank to form a helical pattern.

The helical patterns produced on the cylindrical cam blank by the unique method and apparatus disclosed herein are in the form of a cylindrical spiral which is sometimes a closed loop and sometimes shaped like a sine wave and which can have a constant slope or variable slope, with reversals of direction both axially and circumferentially, and with partial or plural revolutions, all of which are generated precisely and efficiently directly from a linear pattern on a template.

Additionally, it is to be understood that the following description is just as applicable to a method and apparatus wherein a surface of a cam blank is etched, grooved, or otherwise marked with a helical pattern corresponding to a given linear pattern. Accordingly, while the terms cutter, and cutting, and incision are employed hereinafter, they are deemed to include, within their meanings, means for marking, grooving, etching, and the like, a surface of a cam blank.

In general, the method of the present invention provides for the formation of a helical pattern on a cylindrical cam blank which corresponds to a given linear pattern. The linear pattern can take various forms and includes any pattern which defines the path of a moving point whether the path be curved or straight. The method includes scanning the linear pattern at a predetermined rate to sense its shape, rotating the cam blank 10 about an axis 12 at a rate which is a function of the scanning rate, and marking or cutting the rotating cam blank at point 14 whose location axially varies with the shape of the linear pattern. The rotary pattern formed on the cam blank can be a superficial removable marking, a groove, or the truncated end of the cam blank 10, so long as its helical shape corresponds to the linear shape of the predetermined pattern. The shape of the linear pattern can be sensed in terms of its instantaneous lateral-variations, or in terms of its instantaneous displacement from a reference such as reference line 16. In either case the invention provides for varying the axial marking or cutting position as a function of the pattern shape.

In the preferred method, the scanning, rotating, cutting, and varying steps are performed simultaneously and are related to the scanning in such a way that the rotation rate is proportional to the predetermined scanning rate, and the instantaneous axial cutting distance of the incision point 14 is proportional to the instantaneous lateral displacement of the linear pattern relative to the reference line 16. As used herein, axial cutting distance shall be identified so as to include the distance between the incision point 14 and any reference plane normal to the longitudinal axisof rotation of the cylindrical cam blank 10. v

Speaking generally now of the apparatus for accomplishing or working the above-described method, it includes a scanner means 18 for traversing the linear pattern, such as an edge 20 of a prototype template 22 in a direction parallel to the reference line 16 to sense the instantaneous lateral displacement of the edge of the template relative to the reference line. Cutter means 24 is provided for cutting the cam blank 10 at the incision point 14; and drive means 26 is included for moving the scanner means 18 relative to the template 22 at a predetermined scanning rate and rotating the cam blank 10 at a rate proportional to the scanning rate. As the cam blank 10 is rotated about its axis 12 by the drive means 26, the cutter means 24 cuts the cam blank 10 at the incision point 14 which is displaced from the axis 12. In this regard, the axial cutting distance of the incision point 14 is regulated throughout the operation to be always proportional to the instantaneous lateral displacement of the linear pattern relative to the reference line 16. Means 28 is provided for varying the axial cutting distance in the aforesaid manner through operative association with the scanner means 18 as will be described hereinafter.

Referring more particularly to the preferred embodiment of the apparatus as shown in FIGS. 1, 2 and 3, two pins'30 are attached to a support table 32 removably mounting the template 22 in a generally horizontal position on the support table, the left edge of the template being coincidental with the reference line 16 for purposes of discussion. The pins 30 are sized .and spaced to fit a pair of holes 34 in the support table 32 and are long enough to secure the template 22 above the support table on a spacer 35, to allow for optimum operative contact of the scanner means 18 with the template 22 as will be described hereinafter.

During the scanning operation the template is secured by an overlying restraining bar 36 which is attached to the support table 32 by a bolt 38. The support table 32 includes other pairs of holes such as 40, 41, 42 to allow the template 22 to be secured in various positions parallel with and relative to the reference line 16. In the illustrated form the location of the holes 34 relative to the various pairs of holes 40, 41, 42 allows the template 22 to be turned over and repositioned without changing the location of a first end 44 and a second end 46 of the linear pattern as defined by the template edge 20. It is also possible to reposition the template 22 so that the first and second ends 44, 46 exchange locations, such repositioning being accomplished either by turning the template over or by turning it end for end without turning it over. The importance of such features in producing finished cams having recurring reflective or reversed patterns will be discussed hereinafter.

The support table 32 is fixedly attached to the top of a cross slide 48 supported in a dovetail way 52 of a carriage 50 for sliding movement transverse to the carriage 50 and in a direction parallel to the reference line 16. Thus, in the illustrated form of the invention, movement of the scanner means 18 relative to the template edge 20 in a direction parallel to the reference line 16 is accomplished by moving the cross slide 48 along the dovetailed way 52 transverse to the carriage 50 the scanner means being fixed.

While the scanner means 18 is scanning the linear pattern defined by the edge 20 of the template 22, the cam blank 10 is rotated about the axis 12. As represented, the'cam blank 10 is either a solid or hollow cylinder and is removably mounted as by brackets 56 to rotary table 58 with the longitudinal axis of the cam blank disposed horizontally in alignment with an axle 60 of the rotary table. The axle 60 is journalled in an upstanding plate 62 fixedly connected through an angle iron 64 to the carriage 50. A bevel drive wheel 68 on the axle 60 is engaged by a matching bevel gear 70 on a horizontal drive shaft 72 parallel to the reference line 16 (See FIG. 2). A manual turning of a crank handle 74 secured to the drive shaft 72 rotates the bevel drive gear 68 and hence the rotary table 58 to turn the cam blank 10 about the axis 12.

The bevel gear 70, drive shaft 72, and crank handle 74 comprise a portion of the previously referred to drive means 26 for simultaneously rotating the cam blank 10 and moving the scanner means 18 relative to the template 22 at a predetermined scanning rate. The balance of the illustrated drive means includes a continuous drive chain 76 passing around a drive sprocket wheel 78 on the drive shaft 72 and a transfer sprocket wheel 80 on a transfer shaft 82. The drive means 26 also includes a gear train 84 and a driven shaft 86 carrying a lead screw 88 mating with a threaded sleeve 90 fixedly connected to t-hecross slide 48. The-transfer shaft 82 is journalled at opposite ends in support plates 91 and 92 connected to the cross slide 48 for movement therewith parallel to the drive-and driven shafts 72 and 86. The transfer sprocket wheel 80 is maintained in alignment with the drive sprocket wheel 78 by a pair of spacer arms 93 and 94 extending upwardly from the carriage 50 on opposite sides of the transfer sprocket wheel with aligned holes for receiving the transfer shaft 82. To permit axial movement of the transfer shaft 82 with the cross slide 48 relative to the transfer sprocket wheel 80, the transfer shaft includes a longitudinally extending keyway 95 and the transfer sprocket wheel includes a spline (not shown) for riding in the keyway. Thus arranged, rotation of the drive sprocket wheel 78 in response to a turning of the hand crank 74 is transferred to the transfer sprocket wheel 80 by the continuous chain 76. The turning of the transfer sprocket wheel 80 produces a like turning of the transfer shaft 82 and a turning of the driven shaft 86 through the gear train 84. As the driven shaft turns, the lead screw 88 turns in the threaded sleeve 90 to produce transverse sliding movement of the cross slide 48 along the way 52in the carriage 50 and hence movement of the template 22 along and relative to the stationary scanner means 18. It is thus appreciated that rotation of the drive shaft 72 causes the cross slide 48 and therefore the template 22 to be moved relative to the scanner means in a direction parallel to the reference line 16 while at the same time causing proportional rotation of the cam blank about the axis 12. The proportional and directional factors relating the scanning rate and the rotational rate are determined by the size and arrangement of the gears within the gear train as will be described hereinafter.

While the drive means 26 is simultaneously moving the linear pattern along the scanner means 18 and rotating the cam blank 10 about the axis 12, the cutter means 24 is cutting into the cam blank and, in response to operation of the control means 28, is cutting the wall of the cylindrical cam blank to form a helical pattern corresponding to the linear pattern. In this regard, the cutter means 24 contacts the cam blank 10 at the incision point 14 displaced from the axis 12 and on a line therewith normal to the reference line 16. As changes occur in the lateral displacement of the linear pattern from the reference line 16, the means 28 changes the axial cutting distance'of the incision point 14 to maintain the axial cutting distance proportional to the instantaneous lateral displacement of the linear pattern.

To accomplish this, the illustrated form of the cutter means 24 comprises a conventional milling machine 96 fixed to a stationary frame 98 for the apparatus and including a vertical milling spindle 99 mounted in a milling head 100 for rotation about a substantially vertical axis in response to operation of a drive motor (not shown). The spindle 99 engages the cam blank 10 at the incision point 14 to cut a path in the outer surface of the cam blank and in some instances is of sufficient length to extend downwardly through the surface of a hollow cylindrical cam blank 10a as shown in FIG. 5. The invention contemplates the use of variously sized and shaped milling spindles as well as other marking or cutting elements to form the desirable helical pattern in the cylindrical cam blank 10 during rotation thereof relative to the turning spindle.

To maintain the axial cutting distance of the incision point 14 proportional to the instantaneous lateral displacement of the linear pattern relative to the reference line 16, the means 28 comprises apparatus responsive to the operation of the scanner means 18 for longitudinally moving the carriage 50 and hence the rotary table 58 and cam blank 10 toward and away from the turning spindle 99. In this regard, the carriage 50 is sup ported for longitudinal sliding movement in a horizontal plane and in a direction normal to a vertical plane including the reference line 16. Such support for the carriage 50 is most fully represented in FIG. 3 and comprises a longitudinally extending dovetail way 102 for riding along a pair of stationary guide rods 104 fixed to the support frame 98.

The apparatus of the means 28 responsive to operation of the scanner means 18 for maintaining the axial cutting distance proportional to the lateral displacement of the linear pattern relative to the reference line 16 may take various forms. Therefore, it is by way of example only that the illustrated means 28 comprises a piston 106 supported within a cylinder 108 and connected to the frame 98 by a horizontal piston rod 110. The cylinder 108 is fixedly secured to the carriage 50 and is adapted to slide on the piston 106, and hence produce longitudinal movement of the carriage 50 along the way 102, in response to fluid pressure differentials across the piston within the cylinder. In this regard, air hoses 112 and 114 are connected at right and left ends of the cylinder (when viewed in FIG. 1 and to a conventional valve controller 116 included in the illustrated form of the scanner means 18. Compressed air is supplied from a source through an inlet hose 118 to the valve controller 116 and hence to the air hoses 112 and 114 to the cylinder 108. When the air pressure in the right end of the cylinder 108 exceeds the air pressure in the left end, the cylinder drives the carriage 50 and cam blank 10 to the right until the pressure differential across the piston disappears. When the pressure in the left end of the cylinder 108 exceeds the pressure in the right end, the cylinder drives the carriage S0 and cam blank 10 to the left until the pressure differential disappears. In this manner, operation of the cylinder 108 and piston 106 in response to air pressure differentials across the piston produces movement of the carriage 50 in a horizontal plane and normal to a vertical plane including the reference line 16 to regulate the axial cutting distance of the incision point 14 for the cutter means 24.

Various forms of conventional scanners may be employed to control operation of the illustrated means 28 such that the axial cutting distance is at all times proportional to the instantaneous lateral displacement of the linear pattern relative to the reference line 16. It is therefore by way of example only that the illustrated scanner means 18 includes a vertical tracers'tylus 120 in addition to the conventional valve controller 116. The tracer stylus 120 is of conventional structure having an upper end housed within a cylindrical case 122 where it is connected to the valve controller 116.

As illustrated in FIGS. 2 and 3, the case 122v is vertically supported above the template 22 by a horizontal arm 124. The horizontal am 124, in turn, is connected to a slide member 126. The slide 126 is supported for sliding movement along a dovetail way 128 in a vertical extension of the frame 98 normal to a vertical plane including the reference line 16. Thus, the tracer stylus 120 and valve controller 116 are supported for lateral movement toward and away from the edge 20 of the template 22 to permit preadjustment of the lower end of the stylus relative to the template prior to the start of scanning operation. In this regard, the apparatus includes a horizontal lead screw 130 journalled to the vertical extension of the frame 98. The lead screw threadedly engages the slide member 126 and functions to selectively position the slide along the way 128 and hence to initially set a side of the lower end of the stylus lightly against the edge 20 of the template 22. The previously referred to spacing between the template 22 and the support table 32 allows the lower end of the tracer stylus 120 to extend below the template and assures proper lateral contact between the stylus and the template edge 20.

The connection of the tracer stylus 120 to the valve controller 116 is of a conventional and well known nature. Basically, the lower end of the stylus 120 is supported for limited lateral movement with lateral changes in the moving linear pattern defined by the edge 20 of the template 22. By means of the lateral movements imparted to .the stylus, the lateral changes, and hence the lateral displacement of the edge 20 relative to the reference line 16 are transformed into signals controlling the means 28 to regulate the axial cutting distance of the incision point 14. More particularly, the upper end of the stylus 120 is biased and adapted to control valves (not shown) within the controller 116 such that when the lower end of the stylus is in a median lateral position against the edge 20, the valves within the controller close ports to the air hoses 112 and 114. When the stylus 120 is urged by the edge 20 from the median lateral position away from the reference line 16, as by an increase in the lateral displacement of the pattern, the upper end of the stylus effects an increase of the pressure in hose 114, and a decrease of the pressure in hose 1 12.

When the lateral displacement of the edge 20 relative to the reference line 16 decreases and the biasing of the stylus 120 urges it from its median lateral position towards the reference line 16, the upper end of the stylus member effects an increase of pressure in hose 112 and a decrease of pressure in hose 114.

Thus, as the template 22 is driven with the cross slide 48 along the dovetail way 52, the edge 20 bears against the lower end of the stylus 120. So long as the stylus 120 remains in its median lateral position as pre-adjusted'by the lead screw 130, the hoses 112 and 114 remain closed and the means 28 maintain a uniform and predetermined axial cutting distance for the incision point 14. As the lateral displacement of the linear pattern relative to the reference line 16 begins to decrease, however, the lower end of the stylus 120 moves slightly toward the reference line 16 to effect an opening of the hose 112 through the valve controller 116 and an increase air pressure in the right end of the cylinder 108. This produces a movement of the carriage to the right when viewed in FIG. 1 to reduce the axial cutting distance of the incision point 14. Simultaneously, and since the cross slide 24 is supported by the carriage 50, the template 22 moves toward the stylus 120 to bring the stylus back to the median lateral position. As this occurs the air pressures in the right and left ends of the cylinder balance each other. When the lateral displacement of the linear pattern relative to the reference line 16 begins to increase, a reverse operation takes place, the stylus being urged away from the reference line to effect an opening of the hose 114 leading to the left end of the cylinder 108. This produces a movement of the carriage 50 to the left to increase the axial cutting distance of the incision point 14 simultaneously with a return of the stylus 120 to its median lateral position and a balance of air pressures across the piston within the cylinder.

From the foregoing discussion, it is appreciated that the scanner means 18 and the means 28 combine to form a servomechanism for continuously maintaining the stylus 120 in a median lateral position despite changes in the lateral displacement of the edge 20 of the template 22 relative to the reference line 16. In this manner, the servomechanism continuously maintains the axial cutting distance of the incision point 14 proportional to the instantaneous lateral displacement of the linear pattern defined by the edge 20 relative to the reference line.

In the foregoing description, the operation of the means 28 and scanner means 18 has been described with reference to the edge 20 of the template 22 facing away from the reference line 16. When it is desired to shape the cam blank 10 with the edge 20 of the template 22 facing toward the reference line 16, it is necessary to reverse the connections of the air hoses 112 and 114 to the ends of the cylinder 108 and to preadjust the scanner means 18 with the lead screw such that the lower end of the stylus 120 is initially in a median lateral position and biased toward the edge 20 facing the reference line 16. Having made the foregoing hose connection changes and preadjustment of the stylus 120, the operation of the scanner means 18 and means 28 to control the axial cutting distance to be proportional to the instantaneous lateral displacement of the edge 20 from the reference line 16 is substantially as previously described.

As mentioned before, the proportional and directional factors relating the scanning rate of the scanner means 18 and the rotational rate of the cam blank l0are determined by the arrangement of the gears within the gear train 84. Referring more specifically to FIG. 4, the gear train 84 is represented as including a relatively small spur gear 132 supported for turning with the transfer shaft 82 and mating with a relatively large reduction gear 134. The reduction gear 134 is supported for turning and axial sliding movement on a short axle 136 pinned to a pivot plate 138. The pivot plate is supported for swinging movement on the transfer shaft 82 and the axle 136 is adapted to ride in an arcuate slot 142 in the support plate 92 for the transfer shaft. Fixed to an outer face of the reduction gear 134 is a second reduction gear 144 of one-half the radius of the reduction gear 134. The reduction gear 144 is illustrated in FIG. 4 as mating with an idler gear 146 connected to the support plate 92. The idler gear mates with either of two reversing gears 148 and 150 carried on a plate 152 hinged for swinging movement on the driven shaft 86. In this regard, a pin 154 extends from the support plate 92 through an arcuate slot 156 in the plate 152 to receive a locking nut 158 for securing the pivot plate in one of twopositions. The first position is with the reversing gear 148 mating with the idler gear 146 and the reversing gear 150 mating with a idler gear 160 on the driven shaft 86. The second position is with the reversing gear 148 disengaged from the idler gear 146 and the reversing gear 150 mating with both the idler gear and the spur gear 160.

With the gear train 84 arranged as illustrated in FIG. 4, that is with the reduction gears in the first position, a turning of the transfer shaft 82 produces a turning of the driven shaft 86 to drive the cross slide 48 away from the viewer in FIG. 1. The gear reduction provided by the gears 134 and 144 is such that the scanner means 18 scans the entire edge 20 of the template 22 from the ends 44 to 46 while the cam blank is rotated through a full 360. When it is desired to change the gear ratio to provide for a complete scan of the edge while rotating the cam blank 180, the pivot plate 138 is swung upwardly to disengage the reduction gear 144 from the idler gear 146 and the reduction gears 134 and 144 are slipped forward such that the reduction gear 134 mates with both the spur gear 132 and the idler gear 146. With such an arrangement, it may be desired to reverse the scan of the template 22 after completing a 180 rotation of the cam blank 10. This may be accomplished by swinging the plate 152 and the reversing gears 148 and 150 to the second position. When this occurs, the cross slide 48 and hence the template 22 will move forward toward the viewer in FIG. 1 while the cam blank 10 continues to rotate in the same direction.

From the foregoing, it is to be appreciated that changes in the scanning direction accompanied by changes in the position of the template 22 on the cross slide 48 may be undertaken to produce different helical patterns on the rotating cylindrical cam blank 10. For example, the template 22 may be used to produce finished cams having a repeating path by positioning the template 22 as shown in FIG. 2 and scanning along the template edge 20 from its first end 44 to its second end 46 while the cam blank 10 is rotated 180. The template 22 is then turned over so that its first and second ends 44, 46 exchange locations, at which time the reversing gear 148 is disengaged from the idler gear 146 and the reversing gear 150 is engaged thereto. Scanning is then effected in reverse along the template edge 20 from its newly located first end 44 to its newly located second end 46 while the cam blank 10 is rotated in the same direction through another 180.

A finished cam having a reflected repeating path is cut initially as described above, except that midway through the operation when the template 22 is repositioned, it is turned end for end without turning it over,

, so that its first and second ends 44, 46 exchange locations. At this'time, it is also necessary to reverse the connections of air hoses 112 and 114 since the template edge 20 is now facing toward the reference line 16. Scanning is then effected in reverse as described above.

In the foregoing exemplary description, all of the scanning is done while the idler gear 146 is engaged by the reduction gear 134 in order that the cam blank 10 is rotated only 180 while the template edge 20 is scanned from one end to the other. Of course, different sized reduction gears can be employed to provide different degrees of rotation for each scan of a template.

It will be appreciated from all of the foregoing that, although a specific embodiment has been illustrated and described, the invention contemplates the use of variously shaped linear patterns in,conjunction with apparatus providing a unitary proportional factor between the instantaneous lateral displacement of the linear pattern and the related changes in the axial cutting distance, and with apparatus which also provides various proportional factors between the predetermined scanning rate along the linear pattern and the rotation of the cam blank. Changes and modifications may be made in the exemplary form without departing from the spirit of the invention. It is therefore intended that the present invention be limited in scope only by the terms of the following claims.

I claim as my invention:

1. A method of forming a cam having a helical pattern corresponding to a given linear pattern comprising the following simultaneous steps:

scanning the linear pattern in a first direction at a predetermined rate to sense instantaneous lateral changes in said linear pattern;

rotating a cylindrical cam blank about its longitudinal axis and in a fixed lateral position and at a speed which is a function of said predetermined rate; and

cutting a helical pattern in said rotating cylindrical cam blank by moving a cutter relative to said cylindrical cam blank in the direction of said axis and at an axial cutting position which varies with the instantaneous lateral change in said linear pattern.

2. The method of claim 1 including:

sensing the instantaneous lateral displacement of said linear pattern relative to a predetermined reference as said linear pattern is scanned, and

simultaneously varying said axial cutting position as a function of said instantaneous lateral displacement. 3. The method of claim 2 wherein said steps include rescanning at least a portion of said linear pattern in a direction opposite to said first direction.

4. The method of claim 2 wherein said steps include flipping said pattern and rescanning at least a portion of said pattern. v

5. Apparatus for forming a cylindrical cam blank into a cam having a helical pattern corresponding to a given linear pattern, including:

scanner means for traversing the linear pattern and for sensing the instantaneous lateral changes thereof relative to a predetermined reference line;

first mounting means mounting said cylindrical cam blank for rotation about its longitudinal axis, while preventing movement of said cylindrical cam blank in a direction normal to said axis of rotation;

cutter means for cutting the rotating cylindrical cam blank at an incision point displaced from said axis of rotation;

second mounting means fixedly mounting said cutter means in a direction normal to said axis of rotation;

drive means for moving said scanner means along the linear pattern at a predetermined scanning rate and for rotating the cylindrical cam blank relative to the cutter means about said axis at a rotation rate proportional to said scanning rate; and

means operatively associated with said scanner means and said first and second mounting means for providing relative movement between said cylindrical cam blank and said cutter in the direction of said axis for cutting said helical pattern, and said last mentioned means being responsive to the instantaneous lateral changes sensed means supporting a cylindrical cam blank for rotation about its longitudinal axis;

cutter means for cutting said cylindrical cam blank at an incision point having an axial cutting distance thereby for varying the axial ttin iti n as a measured fromva reference plane normal to the function of instantaneous lateral displacement of longitudinal axis Qfsald cylindrical Cam blank; said lin ar att n fro id reference 1i second drive means for rotating said cylindrical cam 6. Apparatus for forming a cylindrical cam blank into blank about said axis at a late Proportional to Said a cam having a helical pattern corresponding to a given predetermined rate of movement of said template; linear pattern, including: and

scanner means for traversing the linear pattern and me ans f' l p f of y fy' for sensing the instantaneous lateral changes "8 saldfixlalcutllllg l tlce ofsald incision point thereof relative to a predetermined reference line; to comlnuany l f Said axial clmmg llstance cuttermeans for cutting said cylindrical cam blank at propomoniil to said mstaftaneous metal dlsplace' and incision point displaced from its longitudinal i of sa1d edge of said tefnplate as sensed by axis; 7 I 1 I W i said tracer stylus, whereby simultaneous rotation means for supporting said cylindrical cam blank of said cylindrical cam blank and variation of said drive means for moving said scanner means along the i g g fgg g g g l ggf gl figgi gl gg%mfiwgg meat pattern a P q scanmng rate said linear pattern defined by said edge of said and rotating sa1d cylindrical cam blank relative to template said cutter means about said axis at a rotation rate Apparatus as in Claim 8 wherein said means for Proportional to S Scanning rate Said drive varying said axial cutting distance includes: means including means for y g said seaming hydraulic piston means for moving said cylindrical rate relative to Said rate of rotation of Said cylindricam blank relative to aid cutter means and in an I Cal Cam blank;al1d axial direction passing through said incision point;

means operatively associated with said scanner d means and resp nsiv t the instantaneous at ral valve means for controlling the movement of said changes sensed thereby for moving said cutter hydraulic piston means, said valve means being acmeans relative to said cylindrical cam blank to tuated by changes in said instantaneous lateral dischange the position of said incision point in the placement of said edge of said template as sensed direction of said longitudinal axis as a function of by said tracer stylus. instantaneous lateral displacement of said linear 10. The apparatus of claim 9 including: I pattern from said reference line. mounting means for securing said template in a new 7. Apparatus as in claim 6 wherein said drive means position after a first scan of said pattern with said includes means for reversing the direction of scanning ffifelence line'parallel to said scanning direction; relative to the direction of rotation of said cylindrical and cam bl k, prepositioning means for moving said template and 8. Apparatus for forming a cam including: mounting means laterally'relative to said stylus to a template having an edge defining a given linear pat- 40 bring g f Said mp against Said y f tern relative to a predetermined reference line on at 3 P i Q a displacement from said i template; reference line identical to thedisplacement of a first drive means for moving said template at ,a l' PQ on sa1d edge at the completlon of predetermined rate in a scanning direction parallel sa1d first Scan. i to said reference line; ll. The apparatus of claim 10 wherein said preposia tracer stylus adapted to contact said edge of said "omng "1 W furthel' mcll ldes means movmg sa1d template to sense its lateral displacement relative template sa1d scannmg dlrectlonto said reference line; 

1. A method of forming a cam having a helical pattern corresponding to a given linear pattern comprising the following simultaneous steps: scanning the linear pattern in a first direction at a predetermined rate to sense instantaneous lateral changes in said linear pattern; rotating a cylindrical cam blank about its longitudinal axis and in a fixed lateral position and at a speed which is a function of said predetermined rate; and cutting a helical pattern in said rotating cylindrical cam blank by moving a cutter relative to said cylindrical cam blank in the direction of said axis and at an axial cutting position which varies with the instantaneous lateral change in said linear pattern.
 2. The method of claim 1 including: sensing the instantaneous lateral displacement of said linear pattern relative to a predetermined reference as said linear pattern is scanned, and simultaneously varying said axial cutting position as a function of said instantaneous lateral displacement.
 3. The method of claim 2 wherein said steps include rescanning at least a portion of said linear pattern in a direction opposite to said first direction.
 4. The method of claim 2 wherein said steps include flipping said pattern and rescanning at least a portion of said pattern.
 5. Apparatus for forming a cylindrical cam blank into a cam having a helical pattern corresponding to a given linear pattern, including: scanner means for traversing the linear pattern and for sensing the instantaneous lateral changes thereof relative to a predetermined reference line; first mounting means mounting said cylindrical cam blank for rotation about its longitudinal axis, while preventing movement of said cylindrical cam blank in a direction normal to said axis of rotation; cutter means for cutting the rotating cylindrical cam blank at an incision point displaced from said axis of rotation; second mounting means fixedly mounting said cutter means in a direction normal to said axis of rotation; drive means for moving said scanner means along the linear pattern at a predetermined scanning rate and for rotating the cylindrical cam blank relative to the cutter means about said axis at a rotation rate proportional to said scanning rate; and means operatively associated with said scanner means and said first and second mounting means for providing relative movement between said cylindrical cam blank and said cutter in the direction of said axis for cutting said helical pattern, and said last mentioned means being responsive to the instantaneous lateral changes sensed thereby for varying the axial cutting position as a function of instantaneous lateral displacement of said linear pattern from said reference line.
 6. Apparatus for forming a cylindrical cam blank into a cam having a helical pattern corresponding to a given linear pattern, including: scanner means for traversing the linear pattern and for sensing the instantaneous lateral changes thereof relative to a predetermined reference line; cutter means for cutting said cylindrical cam blank at and incision point displaced from its longitudinal axis; means for supporting said cylindrical cam blank, drive means for moving said scanner means along the linear pattern at a predetermined scanning rate and rotating said cylindrical cam blank relative to said cutter means about said axis at a rotation rate proportional to said scanning rate, said drive means including means for varying said scanning rate relative to said rate of rotation of said cylindrical cam blank; and means operatively associated with said scanner means and responsive to the instantaneous lateral changes sensed thereby for moving said cutter means relative to said cylindrical cam blank to change the position of said incision point in the direction of said longitudinal axis as a function of instantaneous lateral displacement of said linear pattern from said reference line.
 7. Apparatus as in claim 6 wherein said drive means includes means for reversing the direction of scanning relative to the direction of rotation of said cylindrical cam blank.
 8. Apparatus for forming a cam including: a template having an edge defining a given linear pattern relative to a predetermined reference line on said template; first drive means for moving said template at a predetermined rate in a scanning direction parallel to said reference line; a tracer stylus adapted to contact said edge of said template to sense its lateral displacement relative to said reference line; means supporting a cylindrical cam blank for rotation about its longitudinal axis; cutter means for cutting said cylindrical cam blank at an incision point having an axial cutting distance measured from a reference plane normal to the longitudinal axis of said cylindrical cam blank; second drive means for rotating said cylindrical cam blank about said axis at a rate proportional to said predetermined rate of movement of said template; and means responsive to operation of said stylus for varying said axial cutting distance of said incision point to continually maintain said axial cutting distance proportional to said instantaneous lateral displacement of said edge of said template as sensed by said tracer stylus, whereby simultaneous rotation of said cylindrical cam blank and variation of said axial cutting distance enables said cutting member to cut and form a helical pattern corresponding to said linear pattern defined by said edge of said template.
 9. Apparatus as in claim 8 wherein said means for varying said axial cutting distance includes: hydraulic piston means for moving said cylindrical cam blank relative to said cutter means and in an axial direction passing through said incision point; and valve means for controlling the movement of said hydraulic piston means, said valve means being actuated by changes in said instantaneous lateral displacement of said edge of said template as sensed by said tracer stylus.
 10. The apparatus of claim 9 including: mounting means for securing said template in a new position after a first scan of said pattern with said reference line parallel to said scanning direction; and prepositioning means for moving said template and mounting means laterally relative to said stylus to bring said edge of said template against said stylus at a point having a displacement from said reference line identical to the displacement of a terminal point on said edge at the completion of said first scan.
 11. The apparatus of claim 10 wherein said prepositioning means further includes means for moving said template in said scanning direction. 